Misc: Fix logic for setting user agent (#4265)

src/invidious/yt_backend/connection_pool.cr

@@ -1,7 +1,6 @@
 def add_yt_headers(request)
-  if request.headers["User-Agent"] == "Crystal"
-    request.headers["User-Agent"] ||= "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/114.0.0.0 Safari/537.36"
-  end
+  request.headers.delete("User-Agent") if request.headers["User-Agent"] == "Crystal"
+  request.headers["User-Agent"] ||= "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/114.0.0.0 Safari/537.36"
 
   request.headers["Accept-Charset"] ||= "ISO-8859-1,utf-8;q=0.7,*;q=0.7"
   request.headers["Accept"] ||= "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8"